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Temporal correlations in neuronal avalanche occurrence.

Lombardi F, Herrmann HJ, Plenz D, de Arcangelis L - Sci Rep (2016)

Bottom Line: Moreover we evidence that sizes of consecutive avalanches are correlated.In particular, we show that an avalanche tends to be larger or smaller than the following one for short or long time separation, respectively.Our analysis represents the first attempt to provide a quantitative estimate of correlations between activity and quiescence in the framework of neuronal avalanches and will help to enlighten the mechanisms underlying spontaneous activity.

View Article: PubMed Central - PubMed

Affiliation: Institute of Computational Physics for Engineering Materials, ETH, Zurich, Switzerland.

ABSTRACT
Ongoing cortical activity consists of sequences of synchronized bursts, named neuronal avalanches, whose size and duration are power law distributed. These features have been observed in a variety of systems and conditions, at all spatial scales, supporting scale invariance, universality and therefore criticality. However, the mechanisms leading to burst triggering, as well as the relationship between bursts and quiescence, are still unclear. The analysis of temporal correlations constitutes a major step towards a deeper understanding of burst dynamics. Here, we investigate the relation between avalanche sizes and quiet times, as well as between sizes of consecutive avalanches recorded in cortex slice cultures. We show that quiet times depend on the size of preceding avalanches and, at the same time, influence the size of the following one. Moreover we evidence that sizes of consecutive avalanches are correlated. In particular, we show that an avalanche tends to be larger or smaller than the following one for short or long time separation, respectively. Our analysis represents the first attempt to provide a quantitative estimate of correlations between activity and quiescence in the framework of neuronal avalanches and will help to enlighten the mechanisms underlying spontaneous activity.

No MeSH data available.


Related in: MedlinePlus

Small avalanches si tend to be followed by short quiet times Δti in normal condition.The quantity δP(Δti < t0, si < s0) as a function of t0 and different values of s0. The bar on each data point is 2σ(Δti < t0, si < s0). Each curve represents an average over all experimental samples in a given condition. (a) Non-driven. (b) Driven. (c) Disinhibited (PTX). Insets: The ratio δP(Δti < t0, si < s0)/σ as a function of t0 for different values of s0; dashed lines delimit the interval (−2, 2). In most cases, δP(Δti < t0, si < s0)/σ is much larger than 2. Therefore these results are significant at a level generally lower than 0.05 and give solid evidences of correlations between avalanches and following quiet times.
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f4: Small avalanches si tend to be followed by short quiet times Δti in normal condition.The quantity δP(Δti < t0, si < s0) as a function of t0 and different values of s0. The bar on each data point is 2σ(Δti < t0, si < s0). Each curve represents an average over all experimental samples in a given condition. (a) Non-driven. (b) Driven. (c) Disinhibited (PTX). Insets: The ratio δP(Δti < t0, si < s0)/σ as a function of t0 for different values of s0; dashed lines delimit the interval (−2, 2). In most cases, δP(Δti < t0, si < s0)/σ is much larger than 2. Therefore these results are significant at a level generally lower than 0.05 and give solid evidences of correlations between avalanches and following quiet times.

Mentions: To better enlighten the relationship between si and Δti we consider the quantity δP(Δti < t0, si < s0) (Fig. 4). In the normal conditions, for s0 < 5, δP(Δti < t0, si < s0) is positive for t0 < 200 ms and negative otherwise, decreasing, in absolute value, for increasing s0 values (Fig. 4a,b). This behaviour and the relative maximum observed around t0 = 100 ms, indicate that there is an overabundance of small avalanches whose following quiet time is shorter than 100 ms, suggesting that small avalanches tend to be followed by short, rather than long quiet times. On the other hand, in the disinhibited condition (Fig. 4c), for fixed s0 values, δP(Δti < t0, si < s0) does not transition from positive to negative values and is either always positive or negative, depending on s0. This indicates that the correlation sign depends on avalanche size, whereas in the normal condition it depends on quiet times (Fig. 3a,b). For s0 < 4 δP(Δti < t0, si < s0) is positive and, considering error bars, it is nearly constant over a large range of t0. Therefore we do not observe a very close relationship between small avalanches and short following Δt. Moreover, since for s0 > 6 δP(Δti < t0, si < s0) is always negative or zero, Fig. 4c clearly shows that, in the disinhibited condition, large avalanches are generally uncorrelated to following Δt.


Temporal correlations in neuronal avalanche occurrence.

Lombardi F, Herrmann HJ, Plenz D, de Arcangelis L - Sci Rep (2016)

Small avalanches si tend to be followed by short quiet times Δti in normal condition.The quantity δP(Δti < t0, si < s0) as a function of t0 and different values of s0. The bar on each data point is 2σ(Δti < t0, si < s0). Each curve represents an average over all experimental samples in a given condition. (a) Non-driven. (b) Driven. (c) Disinhibited (PTX). Insets: The ratio δP(Δti < t0, si < s0)/σ as a function of t0 for different values of s0; dashed lines delimit the interval (−2, 2). In most cases, δP(Δti < t0, si < s0)/σ is much larger than 2. Therefore these results are significant at a level generally lower than 0.05 and give solid evidences of correlations between avalanches and following quiet times.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837393&req=5

f4: Small avalanches si tend to be followed by short quiet times Δti in normal condition.The quantity δP(Δti < t0, si < s0) as a function of t0 and different values of s0. The bar on each data point is 2σ(Δti < t0, si < s0). Each curve represents an average over all experimental samples in a given condition. (a) Non-driven. (b) Driven. (c) Disinhibited (PTX). Insets: The ratio δP(Δti < t0, si < s0)/σ as a function of t0 for different values of s0; dashed lines delimit the interval (−2, 2). In most cases, δP(Δti < t0, si < s0)/σ is much larger than 2. Therefore these results are significant at a level generally lower than 0.05 and give solid evidences of correlations between avalanches and following quiet times.
Mentions: To better enlighten the relationship between si and Δti we consider the quantity δP(Δti < t0, si < s0) (Fig. 4). In the normal conditions, for s0 < 5, δP(Δti < t0, si < s0) is positive for t0 < 200 ms and negative otherwise, decreasing, in absolute value, for increasing s0 values (Fig. 4a,b). This behaviour and the relative maximum observed around t0 = 100 ms, indicate that there is an overabundance of small avalanches whose following quiet time is shorter than 100 ms, suggesting that small avalanches tend to be followed by short, rather than long quiet times. On the other hand, in the disinhibited condition (Fig. 4c), for fixed s0 values, δP(Δti < t0, si < s0) does not transition from positive to negative values and is either always positive or negative, depending on s0. This indicates that the correlation sign depends on avalanche size, whereas in the normal condition it depends on quiet times (Fig. 3a,b). For s0 < 4 δP(Δti < t0, si < s0) is positive and, considering error bars, it is nearly constant over a large range of t0. Therefore we do not observe a very close relationship between small avalanches and short following Δt. Moreover, since for s0 > 6 δP(Δti < t0, si < s0) is always negative or zero, Fig. 4c clearly shows that, in the disinhibited condition, large avalanches are generally uncorrelated to following Δt.

Bottom Line: Moreover we evidence that sizes of consecutive avalanches are correlated.In particular, we show that an avalanche tends to be larger or smaller than the following one for short or long time separation, respectively.Our analysis represents the first attempt to provide a quantitative estimate of correlations between activity and quiescence in the framework of neuronal avalanches and will help to enlighten the mechanisms underlying spontaneous activity.

View Article: PubMed Central - PubMed

Affiliation: Institute of Computational Physics for Engineering Materials, ETH, Zurich, Switzerland.

ABSTRACT
Ongoing cortical activity consists of sequences of synchronized bursts, named neuronal avalanches, whose size and duration are power law distributed. These features have been observed in a variety of systems and conditions, at all spatial scales, supporting scale invariance, universality and therefore criticality. However, the mechanisms leading to burst triggering, as well as the relationship between bursts and quiescence, are still unclear. The analysis of temporal correlations constitutes a major step towards a deeper understanding of burst dynamics. Here, we investigate the relation between avalanche sizes and quiet times, as well as between sizes of consecutive avalanches recorded in cortex slice cultures. We show that quiet times depend on the size of preceding avalanches and, at the same time, influence the size of the following one. Moreover we evidence that sizes of consecutive avalanches are correlated. In particular, we show that an avalanche tends to be larger or smaller than the following one for short or long time separation, respectively. Our analysis represents the first attempt to provide a quantitative estimate of correlations between activity and quiescence in the framework of neuronal avalanches and will help to enlighten the mechanisms underlying spontaneous activity.

No MeSH data available.


Related in: MedlinePlus